Integral membrane proteins constitute an important class of proteins with which are often involved in diverse biological functions, including G-protein coupled receptors (GPCRs), channels, transporters and enzymes. Approximately 20-35% of the open reading frames (ORFs) in the human genome are predicted to encode membrane proteins. Membrane proteins account for more than 50% of current drug targets. Structural information about these pharmaceutically useful membrane proteins will assist in the design of better drug molecules. However, despite the need for identifying membrane protein. structures, there are significantly fewer structures available for membrane proteins than for soluble proteins. Some of the major hurdles associated with membrane protein purification include the production of insufficient yields and the inability to obtain diffraction quality crystals.